Influence of climatic factors on pavement moisture and long-term performance of unbound pavement with sprayed seals

Road pavement rehabilitation entails substantial costs for governments worldwide, with annual expenditures reaching billions of dollars. Moisture infiltration emerges as a primary cause of road failures. In Australia and New Zealand, a major share of surfaced roads is constructed with sprayed seals or chip seals due to their cost-effectiveness. However, the permeable nature of these seals renders the pavements susceptible to moisture-induced degradation. Moisture exchange through these seals, influenced by prevailing climatic conditions, triggers temporal moisture variations in pavement layers throughout the service life. These fluctuations, induced by climatic effects, detrimentally affect the shear strength and stiffness properties of pavement materials, leading to road failures. Consequently, incorporating these temporal moisture dynamics into pavement design becomes imperative. Yet, the current Australian pavement design framework lacks advancement in addressing climatic influences, constituting a primary limitation. The absence of precise models to forecast long-term. moisture variations, considering climatic factors, underscore this deficiency.

To address this gap, the authors developed a computer model integrating daily climatic variations to predict moisture fluctuations in unbound pavements with sprayed seals, by capturing the essential physics of unsaturated soil mechanics. This paper elucidates a long-term pavement performance analysis utilizing the developed model. It evaluates the effect of daily climatic conditions on long-term pavement performance, based on numerical results obtained for three climates in Australia. Moreover, it reveals moisture variation patterns in terms of Degree of Saturation (𝑆𝑟) and (s) over a 10-year service life and evaluates key parameters defining the pavement’s service moisture condition and temporal fluctuations of pavement layers.